SELECT statement Processing in an Oracle Database - DBArch Video 7
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- Опубліковано 8 лют 2025
- You will learn from this video how a SELECT statement is processed in an Oracle Database. You will learn about the a Parse, Execute and Fetch phases in a select statement.
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"If you can't explain it simply, you don't understand it well enough" ... You have explained simplest of all .... You understand it perfectly. The auditorium is happy to follow such great videos for Oracle.
This video is the most helpful and concise video on SQL execution. Thanks man
I have attended core dba in multiple institutes and noone is not as clear as you. Your way of explanation is so easy to understand and concepts are explained very clearly...keep up the good work
Best explanation I ever seen..I was searching for right guide for oracle and I found it..Thanks for your effort..We are expecting more videos.
Best teaching ever seen unbeleivable!!!!! May GOD guide you to the truth about HIM. It is the best gift someone can get in his life.
Thanks Stafan.... Enjoy learning...
Everything is nice. Presentation, Technic, Explanation. May god bless you.
You are the best of all...My heart satisfies with ur explanations with valid reasons that u provide..please make the practical scenarios also for all ur videos
...and also please make the videos on Oracle Apps DBA with practical scenarios..
Sir!! I salute you... you know what you are teaching, congratulations
Thanks.. enjoy learning
Hi Ram. How are you? Glad to see you on youtube. Had attended one of your fabulous sessions in Dubai a few years ago. Greetings!!
Best teacher ever... God for dba folks
Thanks... Enjoy learning
Ramkumar Swaminathan seriously sir....in my entire schooling college and work life... Never found such an amazing learning exp....thanks a ton 👏
Very clear and simple, easy to understand explanations for the concepts. Awesome sir. I was searching for these concepts in youtube like anything, fortunately, I found your videos.:))
Excellent explanation. Thank you🙏 sir.
Really, very nice explanation... You explained such a complex stuff in a very simple manner.. Thank you Sir :)
Thanks, enjoy learning...
Hi Sir , Thank you for all your valuable time & energy for making the videos on the oracle Dba and sharing the knowlede.
Request:Please make a video on Multitenant Architecture in 12c .
Thanking you in advance.
Thank you very much for explaining the subject of oracle in a way that everyone can understand.
Best explanation Sir. _/\_ I was looking for a proper guidance on this. The way you explain every details seems so easy. Thank you.
Sir ji thanks a lot.
You are beyond best. I don't have word to adjectify you.
Namaste
Thanks... Enjoy learning
Amazingly explained sir
I have watched all your series and i really like your style of teaching.
Can you do a video series on Postgresql
it's Very Good Videos. explained in simple method. thanks
+Dayashankar Sharma thanks
Thank you sooo much, superbly explained and understood.
Regards,
Sujaa
Short and informative video
Good explanation ...DONE...
Nice Sir...Thank you very much your help...
Great video
SUBSCRIBED YOUR CHANNEL🙏 I'm pretty feeling comfortable listening to your classes. Thank you sir.
nice background music but pls reduce the volume , sometimes its overlapping your voice.
Nothing we can say about your teaching skills.hats off
Thanks...Enjoy learning... BG music is taken care in new videos
Sir,
Thank you for this nice video.Very well explained.
I have a doubt what will happen if the buffer cache is smaller than the table size. Will it get loaded in the memory?
Thanks
It will load in parts one after another part(bunch of blocks) of the table and give you the result
all the videos are very helpful, Thank you so much sir
if you have any Rac Dataguard ASM Videos Link please ?
Kindly look into playlists in my channel, videos are organised into topics you have requested
@@RamkumarSwaminathan ok, Thank you so much sir
Thank you so much ...please upload more videos on RAC.and advanced technologies
+Ashok M will be coming up... Be subscribed
Excellent Tutorial
Thanks you very much. This is very helpful.
+Shiv Vishnoi most welcome... Enjoy learning
Hi Sir,
Your Explonation is very well and I have one doubt which background process will read data from database and read into the DBcahche.
You are the best :) :) :)
Thank you Sir
When soft parse and hard parse will execute?
very best explanation (Y)
You are Amazing
that is awesome thanks a lot...but one question i have is at the time the blocks are send to the buffer cache to process and give data to the app or user. the question is where is the app or user viewing the info ???
is it from the app which the data was send from the server to the app or the app is in the database getting data in the instance still. meaning the process that the app is doing with the data its send back to be updated on the server or instance. they where all processing from the instance all along. so the processes are internal in the instance?
Thank you for your excellent video. I have a question: "How does oracle find table blocks in datafiles ? If table exist in buffer cache, how does oracle find it ?" Thanks.
You can go through my video on Tablespace, Segments, Extents and Blocks ua-cam.com/video/cp56dkTSSNk/v-deo.html All this is maintained and hence when you submit a query, the database is able to identify which blocks belong to the table/s that you are querying...
If the block is present in the Buffer Cache then it reads it from there itself... if not it will have to do I/O and read from the data files in the storage...
After watching video you have suggested, i understand how oracle find table blocks in storage. But in buffer cache, how oracle find it ? What does oracle base on to find ? Thanks for your quick reply.
Buffer cache is only a cache of data files...
Thank you for making this video sir. A few questions,
For how long will an SQL-Area for a corresponding Query be stored in the Shared Pool before it is decided to remove it?
For how long will the Data files blocks be stored in the Buffer Cache before it is erased?
How would this work for queries involving sub-select statements(ex - select * from Emp where Emp.id in (Select id from Managers...))? I'm assuming the Parse-Execute-Fetch process is done on the sub-select statement before the result is returned as a DataFile Blocks to the outer select statement. Correct me I'm wrong.
did you find the answer for this??
@@ManishKumar-qx1kh Nope :( not yet
Hi, can u explain please hard parse and soft parse
Good overview. Thank you. What happens when a hash is generated and later there is a change in DDL? will the hash be deleted and goes for another hard parse??
Example : 1. hash created for select empid from emp;
2. Query executed and result returned.
3. Ddl executed to drop empid column
4. Reissue the same command..
When step 4 executed hash would be same as step 1.. So it should ideally go for soft parse but how this scenario would be handled.??
On every ddl, typically all depended SQLs in the SQLArea are invalidated and will have to be hard parsed again... Thats why dont execute DDLs in a Production database, unless its an off peak hour...
@@RamkumarSwaminathan Thank you for clear explanation
Sir as you said hash is generated again for the same statement on next execution meanwhile oracle documentation says its unique for the same statement because this hash is searched out in shared sql area to avoid a statement from being pasred again on next execution. Please correct where I'm wrong to understand about hash.
when and where is the hash number for your SQL statement created before the database does the shared pool check for a shared area with an exist sql ID? Thank you
Best explanation, it would be even more better if that disturbing background music wasn't included.
Thanks a lot but where is the usage of result cache?
Hi Sir,
Kindly upload a video of " HOW TO CHANGE PLAN HASH VALUE OF A QUERY IF IT TAKES BAD PLAN HASH VALUE INSTAEAD OF REGULAR " and explain it if any impact on execution query.
Sir what is the future of pl sql
Hi Ramkumar,
How to get the details of sql query from server side.
Note: database max number of processes reached. So, we need to kill some of the queries
Hi Sir, are you giving any online training if yes can you please share the details
Thanks
Okay syntax and semantics cleared…. doesn’t this privilege check also actually comes under semantic checks legally? I mean u can make anything but still… I think semantics is about the legal validity...and privileges is one of them I suppose.
Anyway doesn't mean much if in oracle u do things like that but was jus curious. :)
Thanks
Sir I like your way of teaching. but one doubt about your session is that as this is a lecture on regarding oracle, so what is the need of songs and other disturbing things in background. please remove that distraction if possible, as everyone is not comfortable as we are slow learner.
Respects
unable to concentrate due to background music in the video even though you explained it nice
Tq
Kindly remove background score its a distraction
Thank you sir